8 



THE PRODUCTION AND USE OF LIGHT 



so we can show that it is not the liquid kerosene which burns 

 in the case of the kerosene lamp. 



Exercise 5. It is Kerosene Vapor that Burns 



Remove the chimney from the lamp. Light it. Hold the lighted 

 match ready to apply. Blow out the flame. Quickly apply the 

 lighted match to the rising column of smoke. 

 Does it ignite? If not, be quicker in applying 

 the match next time. Repeat the experiment 

 to see how far above the wick you are able to 

 ignite the vapor. 



Have you ever noticed a strong odor of 

 kerosene in the room after " bio wing out" 

 a lamp? (Art. 103.) Explain. Can this 

 be prevented by first turning the wick 

 down so as- to produce a low flame before 

 blowing it out? Explain. 



10. Center Draft Burners. Many large 

 kerosene lamps use circular wicks. They 

 have an open tube extending from the top 

 of the burner down through the center of 

 the bowl to the open central portion of the 

 base. The rim of the base is perforated so 

 that a current of fresh air can readily pass 

 upward through the tube to supply the 

 inside of the flarne. There are, of course, 



Q 



FIG. 8. Center-draft 

 lamp. 



perforations through the sides and bottoms 

 of the burner to supply fresh air to the outside of the flame. 

 Such lamps are known as CENTER DRAFT lamps (Fig. 8). 



III. EVAPORATION, BOILING TEMPERATURE, AND 

 DISTILLATION 



EVAPORATION 



11. Need of New Terms. We have thus far been studying 

 the burning of paraffin in the candle and of kerosene in the 

 ordinary lamp. Gasoline has often been used for producing 



